I enjoy both versions, but I prefer the original.
The Remake OST can feel like a let down. At its worst, it sounds like they gathered up every "epic fantasy blockbuster" musical trope and used it as a soundfont for rearranging the original tracks.
This works well in some cases (Tower Knight, which is was kinda whatever to begin with). However, some of the original motifs were written with a certain timbre in mind (Storm King, Dirty Colossus, Maneater). As a result, they come off as generic and bland when rearranged into something you'd hear in a Lord of the Rings wannabe that was sent out to die in February.
I think the best example of this is Flamelurker. I actually like the new version, but the original told a more interesting story: there's a smoldering, deeply brooding anger emanating from this creature, rather than an explosive rage that's always dialed up to 11.
Dragon God, Maneater, and Dirty Colossus are the tracks that irk me the most.
Dirty Colossus isn't this glorious titan that deserves a bombastic theme with a choir. It's a hunk of crap, bone, and flies that lives among most pitiable group of people in the game.
Maneater's theme is still pretty decent in the remake, but the tension in the original Maneater fight comes from barely seeing the red eyes of these creatures flying around in the dark while also being very, very afraid of the ledges. Now the music is more intense, so a subtler — but possibly more potent — form of dread is replaced with another.
At first glance, Dragon God is very much deserving of a bombastic orchestra and choir, but the neat thing about the original track is that it makes the fight feel more like a careful cat and mouse game with a literal god that can smite you with a single punch. Now it sounds like a generic movie action/chase scene.
Still, some tracks are straight upgrades. Compared to the original, you can hear a pin drop among the whispers in the new version of Old Hero, which is kind of the point of that whole fight. The new song does a better job of telegraphing the fact that this enemy can't see you, so if you're quiet *cough*equip the Thief Ring, idiot*cough*, it won't be a difficult fight.
Old King Allant was a disappointment in the original, and I always thought it should have been switched with the Old One theme. I still enjoy parts of it, but having a fully-fledged refrain of the game's main theme works so much better here, seeing as this is the climatic "real" final boss fight of the game.
Vanguard (originally Penetrator, but it wasn't used for that fight) is one of my favorites in the original, goofy horns and all, and it gets a fresh coat of paint in the remake.
Finally, there's Maiden Astrea. I love, love, love the original, yet I'm happy that Bluepoint took a different approach in the remake. Now we have two excellent variations of the same theme, similar to Gwyn, Lord of Cinder (Dark Souls) and the latter half of Soul of Cinder (Dark Souls III).